.top{
    width: 700px;
    height: 153px;
    float: left;
    margin-bottom: 2px;
}
.banner{
    background: url(./img/banner.jpg);
    width: 700px;
    height: 120px;
}
.nav li{
   float: left;
   text-align: center;
   line-height: 33px;
   width: 100px;
}
.nav a{
   background: url(./img/button1.jpg);
   display: block;
}
.nav a:hover{
    background: url(./img/button1_bg.jpg);
}
